Macrophages from malignant effusions.

Cells from 11 malignant effusions have been examined for macrophage functional attributes and for evidence of macrophage malignancy. Three patients with Hodgkin's disease and one patient with histiocytic medullary reticulosis had atypical macrophages in their serous fluids. This adds further evidence to support the theory that the macrophage is the malignant cell in these tumour types. Two other patients with LRMPS tumours had atypical non-adherent cells in their effusions; these were probably lymphoid in origin. Samples from patients with benign disease and with epithelial tumours did not have atypical LRMPS cells. One patient with Hodgkin's disease lacked the atypical macrophage. In this patient the ascites was not due primarily to tumour involvement. There was no evidence to suggest a Hodgkin's disease-related macrophage deficit as has been reported in tissue samples. It is concluded that cells from malignant effusions are a particularly valuable source of information about the histogenesis of tumours which may be of macrophage origin.